Japanese unexamined patent application publication No. JP-A-2000-250310 (Hereinafter, Patent document 1) describes a related art image forming apparatus. In the related art image forming apparatus, process cartridges are made to be detachably mounted in an apparatus main body.
In an image forming apparatus of this type, no drive source is provided on the process cartridge, and a driving force for rotating photosensitive drums and developing rollers is supplied from a drive source provided in the apparatus main body. For example, a cartridge side coupling is provided on the process cartridge. A drive source and a main body side coupling to which a driving force is transmitted from the drive source are provided in the apparatus main body. When the process cartridge is mounted in the apparatus main body, the main body side coupling is coupled to the cartridge side coupling, whereby the driving force from the drive source is inputted into the cartridge side coupling via the main body side coupling.
In the related image forming apparatus, however, there have occurred cases where the main body side coupling is not coupled to the cartridge side coupling properly.
The invention has been made with a view to solving the problem and an object thereof is to provide an image forming apparatus which can attain an ensured engagement of a drive transmission member (a reciprocating member) with a drive input member.